Karl Pearson 
221 
in the bacilli per leucocyte, the large and small numbers of bacilli appear to be 
distributed more at random within the groups of 50 in the record. 
(v) The results reached are consonant with the " enormous working errors," 
being for the most part the variations of random sampling ; they are not consonant 
with any wide differentiation resulting from defective technique or from serious 
individual peculiarities in counting and recording. 
It seems to me accordingly that Sir Almroth Wright's statement that he, 
"his fellow-workers" and "a very large and increasing number of bacteriological 
workers all over the world " have satisfied themselves that " the enormous working 
errors in opsonic estimations " are merely the functional errors of his critics, who 
in "self-esteem" have attributed them to errors peculiar to the method, requires 
substantiation. I have no prejudice for or against the opsonic index method ; 
for me it is a nice problem in statistics, that is all ; but I should much like 
to see a count of 1000 leucocytes made on a Wright Laboratory slide by one 
of his staff, and then made on the same slide by an independent microscopist 
not trained in Sir Almroth Wright's Laboratory. I hardly think, as at present 
advised, that there would be an appreciable difference in the result. Until this 
be done, it is scarcely scientific — without publishing evidence of any kind — 
to appeal vaguely to the " satisfaction " of " a large and increasing number of 
bacteriological workers all over the world." Statistics on the table, please ! 
I may be quite in error, but at any rate the evidence on which my con- 
clusions are based is here provided for criticism or correction. 
